I'd suggest a two phase approach. 1) come into conformance with the least possible change to current experience, and 2) make the structural change which might change current user experience but provides for assisted access improvement. I'm not a fan of big-change, and I am of a belief most of the current HN mob are pretty OK that it remains much as it is (not that they are unwilling to countenance change but there's a certain curmudgeonly love of this being an un-lovely site. -And I certainly don't think we deliberately don't want to help people who have to rely on semantic element aware readers)